<template>
  <div class="todo-footer">
    <label>
      <input type="checkbox" v-model="allIsChecked" />
    </label>
    <span>
      <span>已完成{{ doneNum }}</span> / 全部{{ todoList.length }}
    </span>
    <button class="btn btn-danger" @click="clearDoneHandle">清除已完成任务</button>
  </div>
</template>

<script>
export default {
  name: "Footer",
  data() {
    return {
      todoList: [],
    };
  },
  computed: {
    doneNum() {
      return this.todoList.reduce((p, c) => (c.done ? p + 1 : p), 0);
    },
    allIsChecked: {
      get() {
        //全选的逻辑,当数组的每个元素的done都是true,则allIsChecked是true,其他都是false
        return (
          this.todoList.every((item) => item.done) && this.todoList.length !== 0
        );
      },
      set(e) {
        //当计算属性的值改变时就会触发set函数(e,是checked的值true/false),把这个e传给app 在app中根据e的值修改todoList的值
        // console.log(e,this.$bus ,'e');
        this.$bus.$emit("getFooterchecked", e);
      },
    },
  },
  mounted() {
    this.$bus.$on("getAllList", (value) => {
      this.todoList = value;
    });
  },
  methods: {
    clearDoneHandle(){
      this.$bus.$emit('getDonechecked')
    },
    
  },
};
</script>

<style scoped>
/*footer*/
.todo-footer {
  height: 40px;
  line-height: 40px;
  padding-left: 6px;
  margin-top: 5px;
}

.todo-footer label {
  display: inline-block;
  margin-right: 20px;
  cursor: pointer;
}

.todo-footer label input {
  position: relative;
  top: -1px;
  vertical-align: middle;
  margin-right: 5px;
}

.todo-footer button {
  float: right;
  margin-top: 5px;
}
</style>